Embodiments of this disclosure generally relate to a fuel tank, and more particularly, to reducing a potential of hazardous conditions within an aircraft fuel tank by cooling ullage in a heat exchanger.
Inerting aircraft fuel tanks may remove potential hazardous situations arising from combustible combinations of oxygen, fuel vapors and ignition sources. Existing solutions for reducing fuel tank flammability may include adulterating ullage within the fuel tank with nitrogen enriched air (NEA) or oxygen depleted air (ODA) that may be generated by an onboard inert gas generating system (OBIGGS), which may be referred to as a nitrogen gas inerting system (NGS) or fuel-tank inerting system (FTIS).
OBIGGS may use compressed air to generate NEA or ODA. OBIGGS may require that the air supplied to it be within a narrow band of pressures and temperatures and that the air be clean, of low humidity and with low ozone and hydrocarbon concentrations.
NEA or ODA may be an asphyxiant, while oxygen enriched air (OEA) may be a potential fire hazard. Hydrocarbon laden gases exhausting from the fuel-tank may be a carcinogenic and also malodorous and unfriendly to the environment. OBIGGS may use a hollow fiber membrane (HFM) in air separation modules (ASM) for generating NEA and OEA. Performance and operation of ASM may be adversely affected by contaminants in the air that they process.
NGS systems may be expensive to develop and certify as they may not be reliably simulated by analysis. They may use substantial auxiliary equipment that is expensive, for example, an ozone converter to dissociate ozone in air, turbo-compressor to ensure air pressure within design limits during low pressure conditions, heat-exchangers to cool and heaters to heat to ensure air supply within design temperature limits, filter to reduce particulate contamination, water separator to remove excessive moisture and oxygen sensor to check the ASM performance. In addition multiple sensors and control devices may be used to monitor the performance of components and to protect equipment from component failures.
Therefore, it would be desirable to provide a fuel tank flammability reduction and inerting system and methods that overcome the above problems.